Field of the Invention
The invention relates to a separating device which can be used to separate elongate solid pieces from other solid pieces.
In many areas of industrial application, it is necessary for solid materials which are contained in bulk material, for example, to be separated into a plurality of fractions. The fractions are generally divided according to different sizes, geometries or qualities of the solid materials. It is always desirable for the solid materials to be separated if the various solid fractions are to be supplied for further treatment.
In the construction industry, for example, building rubbish which is produced is separated from large and bulky debris fractions, which are then sorted and reused. The finer building rubbish which has been separated off is disposed of, for example, at a landfill site that is provided for that purpose.
In the waste disposal field, it is becoming ever more important to separate and sort the waste or remainders produced after waste reutilization in order to be able to dispose of those materials in as environmentally friendly a manner as possible. The separation of the waste may be carried out before reutilization of the waste, but may also form an essential process step in the waste reutilization.
Thermal processes are known for elimination of waste. In those processes the waste is incinerated in refuse incineration plants or pyrolysed, i.e. subjected to a temperature of approximately 400xc2x0 C. to 700xc2x0 C. with the exclusion of air, in pyrolysis plants. In both processes, it is sensible for the material which remains after incineration or after pyrolysis to be separated, in order for it either to be fed for reutilization or to be disposed of in a suitable manner. The aim is to minimize the residual material which ultimately has to be landfilled.
European Patent Application 0 302 310 A1, corresponding to U.S. Pat. No. 4,878,440, and a company publication entitled xe2x80x9cDie Schwel-Brenn-Anlage, eine Verfahrensbeschreibungxe2x80x9d [The Carbonization Plant, A Process Description], published by Siemens AG, Berlin and Munich, 1996, have disclosed, as a pyrolysis plant, a so-called carbonization plant in which essentially a two-step process is carried out. In the first step, the waste supplied is introduced into a carbonization drum (pyrolysis reactor) and carbonized (pyrolysed). The pyrolysis produces carbonization gas and pyrolysis residue. The carbonization gas is burned, together with combustible pieces of the pyrolysis residue, in a high-temperature combustion chamber at temperatures of approximately 1200xc2x0 C. The resultant waste gases are then purified.
In addition to combustible pieces, the pyrolysis residue also contains noncombustible fractions. The noncombustible fractions are essentially composed of an inert fraction, such as glass, stones or ceramic, and a metal fraction. The valuable substances in the residue are sorted out and fed for reutilization. The sorting requires processes and components which ensure reliable and continuous operation.
In order to provide for reliable operation, it is often desirable for solid pieces having a certain geometry to be separated out, so that they do not impair the operation of downstream separating devices for the remaining solid material and enable that material to be separated further. Elongate solid pieces, in particular wire or fine stranded wires, often present a particular problem. Those wires can only be separated from the remaining solid material with very great difficulty and they block screen holes in screens. That is particularly the case if those elongate solid pieces lie below a certain size.
International Publication No. WO 97/26495 has disclosed a discharge configuration which has a conveyor device for conveying and separating pyrolysis residue. The conveyor device has a separating base which has a sawtooth-like profile and is vibrated in order to convey the pyrolysis residue. The fine fractions of the pyrolysis residue collect in the longitudinal grooves which are formed by the sawtooth-like profile. A bar screen for separating the fine fractions which have accumulated from the remaining coarse fractions is disposed at the end of the separating base. A drawback of that configuration is that large, wide and long fractions are also separated off together with the fine fractions, since they can align themselves in longitudinal grooves and fall through the adjoining bar screen. It is not possible to efficiently separate off fine wires or similar elongate solid pieces.
It is accordingly an object of the invention to provide a separating device for elongate solid pieces, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type, which allows effective separation of elongate solid pieces and which permits continuous operation without disruptions.
With the foregoing and other objects in view there is provided, in accordance with the invention, a separating device for elongate solid pieces, comprising a vibrating base having a number of longitudinal grooves extended in a conveying direction, the longitudinal grooves having a depth decreasing along the conveying direction; and screen openings adjoining the longitudinal grooves for separating elongate solid pieces.
Due to the inherent mechanical movement, i.e. the vibrations of the vibrating base, the solid material which is placed onto the vibrating base is conveyed in the conveying direction. The elongate solid pieces are simultaneously aligned in the conveying direction in the longitudinal grooves. At the same time, elongate, wide solid pieces are initially also aligned in this direction. Due to the decrease in the groove depth, these wide pieces then orient themselves essentially parallel to the vibrating base, so that they slide over the screen openings which adjoin the longitudinal grooves. In contrast, the narrow elongate solid pieces fall through the screen openings, which are preferably in gap form, in the manner of a bar screen. The decisive advantage of the screen device lies in the fact that only elongate solid pieces, and not wide solid pieces, are separated off. The screen device is suitable in particular for separating off fine stranded wires which have a diameter of approximately 0.1 to 2 mm and a typical length of up to 15 mm.
The separation of the elongate, narrow solid pieces can be expressed by the following three steps:
a) Alignment of the elongate solid pieces,
b) deflection of wide, elongate solid pieces, and
c) separation of the elongate solid pieces through the screen openings.
In accordance with another feature of the invention, the side walls of the longitudinal grooves have an inclined shape in order to allow simple alignment of the wide solid pieces parallel to the vibrating base.
In accordance with a further feature of the invention, the vibrating base has a wavy profile or a sawtooth-like profile in order to provide for the elongate solid pieces to be aligned as easily and reliably as possible in the conveying direction.
In accordance with an added feature of the invention, the longitudinal grooves and the elongate screen openings in each case run parallel to one another in order to ensure operation without disruption.
In accordance with an additional feature of the invention, the screen openings extend all the way to the end of the separating device, as seen in the conveying direction. They are therefore constructed to be open at the end. This is an essential feature for ensuring that solid pieces do not accumulate or become jammed in the separating device since, for example in the case of an elongate screen opening with a circumferential edge, that piece of the edge which lies in the conveying direction would present a resistance to the flow of solid material. Pieces of material could become suspended from this edge, and could lead to the screen opening becoming blocked and therefore to the function of the separating device being disrupted.
In accordance with yet another feature of the invention, the screen openings widen in the conveying direction, in order to avoid blockages and to ensure that the solid material flows as well as possible. A force is applied in the conveying direction to pieces of material which have become jammed in the screen opening by the solid material which follows. The jammed piece of material can then be moved in the conveying direction and then falls through the widening screen opening.
In accordance with yet a further feature of the invention, for this purpose, the screen opening widens continuously, in particular in a V shape.
In accordance with yet an added feature of the invention, the edges of the screen openings have an elastic construction, in to which case only a slight force has to be applied in order to release any jammed pieces of solid material. At the same time, this reduces the load which jammed pieces of material exert on the separating device as compared to edges which do not have an elastic construction.
In accordance with yet an additional feature of the invention, the screen openings are provided at their edges with elastic tabs which narrow or taper to a point in the conveying direction, so that the screen openings widen in the conveying direction and can be manufactured easily. In this construction, the widening is formed by the tabs.
In accordance with again another feature of the invention, there is provided a cleaning rake with a number of tines. The tines can be introduced into the screen openings and can be moved in the conveying direction in the screen openings. This rake can be used to release any pieces of material which become jammed, so that the separating device can operate continuously. The cleaning rake can be moved when required, periodically or continuously into the screen openings. The widening of the screen openings is highly advantageous for releasing jammed pieces of solid material using the cleaning rake, since the cleaning rake only has to move the jammed pieces of material slightly in the conveying direction for them to be released and fall through the widened screen opening. Moreover, the elastic construction of the edges is particularly advantageous for minimizing the load on the cleaning rake.
In accordance with a concomitant feature of the invention, the vibrating base is made of metal in order to provide for a configuration which is as robust as possible.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a separating device for elongate solid pieces, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.